The invention relates to a machine for flame processing of textile fabric webs, especially a singeing machine with a burner unit comprising a combustion chamber terminating in a singeing slit, said chamber being connected with a gas mixing chamber via a gas feed slot, said slot being partially closeable by means of a damping device to adjust the flame width.
In machines of this type, textile fabric webs are carried past a singeing flame at high speed whereby this same machine is used to process fabric webs of very different widths. The maximum acceptable fabric web width depends on the width of the machine, which is usually several meters. Without suitable devices, a large portion of the singeing flame would burn uselessly during the processing of narrow fabric webs, i.e. high energy costs not required for the flame processing process would result.
A machine is known from German Pat. No. 20 23 782 in which the mixture feed slot to the conbustion chamber can be closed off by a row of strip shaped sealing elements in segments. The device described in that patent can achieve considerable energy savings; however when the sealing element is divided into segments it must generally be taken into account that a portion of the gas will continue to burn uselessly outside the width of the fabric web. In addition, adjustment of the flame width to a new fabric web is labor-intensive, for which reason there is a danger that the operating personnel, for reasons of convenience, will fail to adjust the singeing flame width.
The goal of the invention is to provide a machine wherein the width of the working flame can be adjusted continuously and with low operating expense.
This goal is achieved according to the invention by virtue of the fact that the damping device comprises one or two sealing strips insertable from one or both ends of the burner unit for the mixture feed slot. The important advantage of the end-wise insertion of sealing strips consists in the continuous adjustability of the flame width, so that a precise adjustment to the particular width of web being transported past the flame is possible. The pushing of sealing strips in and out from the ends of the burner unit is clearly simpler than, for example, operating a row of levers, as would be required with a discontinuous adjusting device.
As a result of the invention, the sealing strips can be guided in an expansion channel provided in the side walls of the mixture feed slot. To install a continuous damping device, therefore, a slight change in an already existing component is required without additional fastening devices or the like inside the burner unit being required. The invention can thus be achieved in a simple and cost-effective manner.
According to a preferred embodiment of the invention, the sealing strips can be flexible and wound by their outward end segments respectively upon rotatable winding bodies for adjusting the inward ends of the sealing strips, from which point the sealing strips are guided through guide tubes to the ends of the burner unit. When flexible sealing strips are used, in contrast to rigid rods or the like, the normal width of the machine can be retained. The guide tubes between the winding bodies and the ends of the burner unit can be guided in the same fashion as, for example, cooling tubes or pipes for the gas supply, so that the overall result is an extremely space-saving design. The continuous adjustment of the flame width can be accomplished by using a simple rotary motion.
According to another feature of the invention, the sealing strips can be made gas-permeable to an extent which is sufficient for feeding an igniting flame. This gas permeability of the sealing strips, which can be implemented by holes, slots, or the like, gives the operating personnel the opportunity to ignite the singeing flame from the ends of the burner unit safely even when the flame width is considerably reduced. The resultant gas losses remain extremely low and are insignificant cost-wise.
As a result of the invention, the sealing strips can consist of metal strips twisted into tubes. Tubes twisted in this fashion, so-called spiral tubes, are suitable for various reasons optimally for adjustment of the flame width: they can be made of heat-resistant metal and are still flexible. They can have a high tensile and compressive strength by suitable crimping of the edges of the strips lengthwise and have cross slots arranged regularly at close intervals, ensuring a specific gas permeability.
According to another embodiment of the invention, the machine can have associated with it a conveyor with two edge sensors scanning the edges of the belt, and can be provided with an adjusting device which shifts the sealing strip along the mixture feed slot as a function of the position of the edge sensor. The continuous adjusting device of the damping device according to the invention is especially suitable for automation whereby mechanical, pneumatic, or electrical drives and control devices may be used. The machiine need only be adjusted to the width of the fabric web on the fabric web guide, while the flame width is automatically changed at the same time. Since operating personnel are forced to operate the fabric web guide in any case for proper operation of the machine, optimum energy use will occur at all times.
As a result of the invention, the edge sensors can be adjusted by turning a spindle and the adjusting device can turn the winding bodies depending on the degree of spindle rotation. By using flexible sealing strips, especially spiral tubes, an adjusting device for adjusting the flame width can be produced in an especially simple fashion, because only two rotary motions, one on the fabric web guide and the other on the winding bodies, need be coordinated with each other.
According to a preferred embodiment of the invention, the spindle rotation can be detected by a set value potentiometer, the angular position of the winding bodies can be recorded by an actual value potentiometer, the values on the two potentiometers can be compared in an electronic regulator, and the winding bodies can be adjusted to conform to the preset value. This form of an electrical adjusting device has the advantage over mechanical control, for example, that it is extremely economical and takes up little space.
As a result of the invention, a pressure sensor can be located in the gas mixing chamber to detect an actual value and the machine can be equipped with a regulator which regulates the pressure in the gas mixing chamber to a presettable value by adjusting the gas mixture feed. The flame width and hence the throughput volume of the gas mixture is unavoidably linked with any change in the pressure in the gas mixing chamber, and is also therefore linked to the formation of the singeing flame. Without a regulator, therefore, any change in the width of the fabric web would involve a tedius adjustment of the singeing flame. The advantages of automatic adjustment of singeing flame width become most significant in practice when a suitable regulating device is used to keep a constant pressure in the gas mixing chamber. If such a device is present, however, the overall result is a machine with a high level of operating comfort and minimum energy consumption.